Code Fiddle

Here | Min-width: 530px

N.B.

Slight differences in fiddle and on this page due to presence/absence of summary box. Root variables provided for easier experimentation.

Lorem ipsum
Dolor sit amet
Consectetur
First, Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Second, Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Third, Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Code Fiddle

Here | Min-width: 400px (ideally)

N.B.

Odd leakage of edge of circle behind the mask, although the dimensions should match.

100K

Remark

Hover over the animation to pause it. Lorem ipsum dolor sit amet consectetur adipisicing elit. Obcaecati neque velit, distinctio totam sapiente quasi.